A group supporting the Florida senator has run ads attacking Mr Trump over the allegations, which the property mogul has demanded be pulled. He continued the defence on Twitter the day before the court's ruling, saying the programme had a "98 per cent approval rating". "I could have settled but won't out of principle!" he added.
The lawsuit was brought in 2013 by Eric Schneiderman, New York's Attorney General. Mr Trump has called Mr Schneiderman a "typical politician" who was targeting him because he refused to donate to his campaign.
Mr Schneiderman accused Mr Trump of "racial demagoguery" but said he would not debate with him publicly about an ongoing case. "The state Supreme Court has already ruled that Trump University operated illegally in New York as an unlicensed educational institution, and we look forward to prevailing on the rest of our claims."
The US election went national on "Super Tuesday" yesterday, with 12 states going to the polls and Mr Trump and Hillary Clinton casting broad shadows over the proceedings. Mr Trump has come under constant attacks for everything from the tone of his rhetoric to the size of his hands, but remained poised to win in a majority of contests.
Mrs Clinton, meanwhile, looked to Super Tuesday as the moment she could leave Bernie Sanders behind and become the de facto Democratic standard bearer. She referred just once to Mr Sanders in an election-eve speech in Fairfax, Virginia, instead depicting herself taking the stage in general election debates with Mr Trump.
"I'm looking forward to those debates," she said, "because at some point, you can't just say whatever pops into your head if you want to be the president of the United States of America."